A study of the metabolism of phenolic compounds by pathogenic dematiaceous fungi (black molds) belonging to the genera Fonsecaea, Phialophora, and Cladosporium is proposed. The data derived from experiments described in this proposal will be useful (1) for developing biochemical tests for rapid laboratory identification of these species, (2) for assessing ecological roles that black molds carry on as saprophytes of wood in nature, and (3) for clarifying the controversial taxonomic relationships between black mold pathogens. As a first approach, lignin sulfonate, a readily available mixture of non cellulosic materials including several phenolic compounds derived from wood will be used as a growth medium for black molds. A comparison of the qualitative chemical changes brought about in lignin sulfonate by metabolism of black molds will be determined using column chromatography, thin-layer chromatography, ultrafiltration, and other appropriate techniques. A second approach will involve the use of comparative assimilation tests to determine the ability of black molds to utilize lignin model compounds as sole carbon and energy sources. The third approach will involve extraction, partial purification and characterization of activiies of the enzymes phenolase, laccase, and peroxidase from black molds. Phenolic compounds known to be incorporated into the structure of lignin will be tested as substrates for these enzymes. Preliminary data obtained with such assays have demonstrated significant differences between black mold species with regard to the activities of these three pigment-forming enzymes. Such enzymatic differences offer an approach to development of diagnostic laboratory tests that can be used to shorten the time required for identification of pathogenic dematiaceous fungi.